Combustion control



I May 26, .1925.

. 1,539,257 a. H. GIBSON COMBUSTION CONTROL Filed Aug. 22. 1 22 2 Sheets-Sheet 1 m VENTOR 7335A TTORNEY May 26, 1925. 1,539,257

ca. H. GIBSON CQMBUS'IION CONTROL Filed Aug. 22-. 1922 2 Sheets-Sheet 2 [N V E N T OR 650,664- bf Ema-0N izls A TTORNEY Patented May 26, 1925.

' UNITEDSTATES GEORGE E. GIBSON, 0F MON ICLAIR, NEW JERSEY.

COMBUSTION common.

. Application filed August 22, 1922. Serial No. 583,491.

To all whom it may concern:

Be i known that I, GEORGE H. GIBSON, a citizen of the United States, and resident of Montclair, New Jersey, in the countyof Essex and State of New Jersey, have invented certain new and useful Improvements in Combustion Controls, of which the following is a specification.

The general object of the present invention is to provide improved apparatus for regulating combustion in furnaces heated by the combustion of solid fuel, and my invention comprises simple and effective means for automatically regulating the supply of fuel to the furnace grate as required to maintain the fuel bed resistance to gas flow therethrough approximately constant. The various features of novelty which characterize my invention are pointed out with particularity 'in the claims annexed to and forming a part of this specification. For a better understanding of the invention, advantages possessed by it, and various specific objects attained with it, reference 8 ould be had to the accompanying draw ings and descriptive matter in which I have illustrated and described preferred forms of embodiment of the invention.

Of the drawings:

Fig. 1 is a sectional elevation of a portion of a locomotive in which my invention is embodied;

' Fig. 2 is a sectional elevation of a portion of the control mechanism employed in Fig. 1; and

Fig. 3 is a diagrammatic representation of a modification of the apparatus shown in Fig. 1.

In the drawings, and referring first to the construction shown in Fi s. 1 and 2, A represents a locomotive of w ich A is the grate, A the firebox, A the smoke box, A the rimary air inlet to the ash pit, A the smo estack, A the steam dome, A the steam pipe leading from the steam dome to the valvechest A, of the locomotive, and A the secondary air inlet. The exhaust pi A leads from the valve chest to an ex. aust nozzle B discharging axially through the smoke stack A as is usual. A bellows pressure chamber C has its interior connected by a pipe C to steam pipe A, and has its movable lower end connected to the stem of a needle valve D which throttles the. outlet of the exhaust nozzle B more or less, in inverse relation'to the locomotive steam pressure. Fuel is fed on to the grate A by an automatic stoker mechanism E at a rate regulated by the valveF' controlling the flow of steam through the pipe F from the steam dome of the locomotive to the steam motor E driving the stoker mechanism.

The extent to which the valve F is The pressure regulating means is a differential pressure device comprising a pair of pressure/chambers H and H, having flexible' walls or diaphragms connected to the opposite ends of a lever H the fulcrum H of which can bead'justed lengthwise of the lever by rotating the adjusting screwI-I. The pressure chamber H is connected to the firebox by the pressure transmitting pipe H and the chamber H is connected to the smoke box by the pressure transmitting pipe H. The lever H carries a needle valve H which regulates the leakage from a chamber I (see Fig. 2) through an outlet I. A pipe I connects the chamber I to the pressure motor G. A motive fluid such as compressed air is constantly supplied to the pipe I through the supply-connection I which includes a restricted orifice I".

- With the arrangement described substantially all of the steam generated by the locomotive is discharged in normal operation through the exhaust nozzle B, and the ejector or draft producing effect of the latter is therefore approximately proportional to the rate of steam output fromthe locomotive boiler. The effect of the exhaust nozzle is to create a pressure less than that of the atmosphere in the firebox of the locomotive and a still lower pressure in the smoke box. The drop in pressure between the firebox and the smoke box is a function on the one hand of the volume of flow through the boiler tubes, and on the other hand, of the atmosphere and the pressure in the fire box will vary in proportion to the difference between the pressure of the atmosphere and the pressure in tllu smoke box. Therefore, if the fulcrum H for the lever H is nearer the center of chamber H than to the center of the chamber H when the flexible walls of the two chambers are of the same size, or if the fulcrum is midway between the'centers of the two chambers. and the diaphragm of the chamber H is smaller than. the diaphragm of the chamber H, there will be a certain standard fuel bed resistance to flow which will .maintain the lever H in equi- 'lll'ilililll regardless of whether the rate of combustion isslow or rapid. T he resistance of, thefucl bed to gas flow through it, required to maintain the lever H in equilibrium. can .be adjusted. in. the apparatus shown. by adjusting the fulcrum block H? along the screw H. V The maintenance of a constantfuel bed resistance insures, and with the apparatus of Fig.1 is necessary to securerthe proper influx of secondary air through the inlet A".

YVhen the fuel bed resistance to flow becomes greater than the predetermined standard, the differential between the pressure of the atmosphere and that in the firebox increases relative to the differential between the pressure of the atmosphere and-that in the smoke box, and this shifts the lever H in the direction moving the needle valve H farther into the orifice I and thereby causes the pressure in the pipe I and the'chamber G to buildup. This moves the-valve F in the closing direction, throttles the supply of steam to the stooler motor E, reduces the rate of fuel supply to thegrate and thereby brings about a reduction in fuel bed thickness and resistance. Conversely when the fuel bed resistance falls below the standard value, the lever H is shifted to withdraw the needle valve H somewhat. whereby the pressure in the pipe I and chamber G is reduced, and the valve F is correspondingly opened by the spring G, thus speedinp; up the stolrer motor and restoring the normal fuel bed thickness. In the apparatus of Fig. l. the strong draft prevailing whenthe rate of combustion is high, tends to loosen up the fuel bed, and in consequence tends to the maintenance of a slightly thicker fuel bed when the rate of combustion is high than when the rate of combustion is low.

hen the steam pressure falls below the normal. a valve L connected to the stem of the valve l). and located in the live steam supply connection M to the live. steam auxiliary draft creating nozzle N is opened. thus increasing the'draft and tending to bring the steam pressure up to normal. The automatic control of the draft effected by the discharge through the exhaust nozzle l3. and the pressure chamber C may be supplemented, if desired, by the auxiliary steam supply through the pipe K and manually controlled valve K" to the live steam draft nism as required to maintain a predeter mined ratio between the pressure drop or draft loss in the fuel bed, and the pressure drop or draft lossbetween the smoke box A and the fire box A. v

The effective use of this simpleform of differential device as a fuel supply control ler, requires that the furnace shall be open to the atmosphere, or connectedthereto by a passage of constant flow resistanceat one end or the other of the draft path. In Fig. 1, the furnace is thus open to the atmosphere at the inlet end of the draft path, through the primary air inlet opening A. The invention is not limited, however, to use in a furnace operating under induced draft with atmospheric pressure in the ash pit. It may be used equally well. in a furnace discharging waste gases directly and freely into the. atmosphere and having its ash pit air pressure above that of the atmosphere, as is the case, for example, in the furnace shown in Fig. 0.

In the typical stationary boiler furnace AA diagrammatically illustrated in Fig. 3. the draft creating device is a blower 0 delivering air under pressure to the furnace ash pit inlet A, and A is the outlet pipe through which the waste gases are discharged to the atmosphere. Secondary air is supplied to the furnace chamber above the fuel bed from the ash pit through the bridge wall passage A which may be controlled by a damper A Fuel is supplied to the furnace grate A by a stoker EA operated by asteam motor EA, and the action of the latter is controlled by a differential device comprising chambers H and H exactly as the motor E of Fig. 1 is controlled. In Fig. 3. however, H. the smaller of the two pressure chambers or the one closer to the lever ful' crum H is connected to the furnace ash pit. while the chamber H is connected to the furnace chamber immediately above the fuel loo Similarly the differential to which the flexible wall of the chamber H is Subjected is equal to the sum of the'draft loss in, the fuel bed plus the draft loss from the top of the fuel bed to the waste gas outlet. The apparatus of Fig. 3 thus acts tomaintain a constant ratio between the draft loss in the'fuel bed, and the draft loss through a portion of the furnace in which the How main, and controlling a valve X in the steam supply pipe X to the turbine or other steam motor driving the blower O. The pressure motor 9 increases or decreases the supply of steam to the motor driving the blower O, as the boiler steam pressure decreases or increases. The simple air and fuel supply regulation illustrated in Fig. 3 is especially effective when a battery of boi ers thus controlled deliver steam into the same steam main, as the regulating apparatus then serves not only to keep proper fuel beds in the varying furnaces, but also to properly divide the load among the different boilers.

In each form of my invention illustrated, the resultant of the forces acting on the lever I-I whereby the latter is turned about its fulcrum as the fuel bed resistance changes, is proportional to the difference between the resultant of the pressure in the furnace above the grate and the opposing pressure of the atmosphere acting over one area, and the resultant of the pressure in the furnace adjacent the draft creating device and the opposing pressure of the atmosphere acting over an area of different size. In the particular construction illustrated, the two 0pposing resultants referred to are directly obtained by the action of the furnace and opposing atmospheric pressures on the simiiarly sized flexible wall portions of the chambers H and H, but on account of the unequal distances between the fulcrum of the I, lever H and the points of connection of the a lever to the flexible walls of the pressure chambers H and H, the same effect is ob tained as would be had if the flexible walls of the two pressure chambers were of unequal size but with each acting with the same leverage on the lever H The effect of ad justing the fulcrum axis in the particular construction illustrated, is the same as would be obtained by changing the relative sizes of the flexible wall portions of the chambers H and H without changing the leverage with which they act on the lever H I While in accordance with the provisions I of the stat-utesI have illustrated and Jdescribed the best forms of my invention nowknown to me, it will bevappare'ntto those skilled in the art that many changes may be made in the formsof the apparatus andmodes of operation described-,,witl1out de' parting from the SplI'lb'Q-f myinvention as .set forth in the appended-claims. Certain novel featu'es disclosed i-but not'--:claimed-v herein are claimed in my applicationgserial No 418,087, filed October 19, 11920; ofgwhieh this application is in part a',.;continuation. H avlng now described-my 1n;\"ent1QIi-, Wl1at.

I claim as new and desire 'to-sepurerby,

Letters Patent, is: 2 1M3 1. The combination with acfurnace comand having its primary air inlet and its outlet for gaseous products of combustion connected, one to the atmosphere by a passage of constant flow resistance, and the other to a draft creating device, of fuel supply means automatically responsive to a force proportional to the difference between the resultant of the pressure in the furnace above the grate and the opposing pressure of the atmosphere over one area, and the resaltant of the pressure in the furnace adjacent the draft creating device and the opposing pressure of the atmosphere over an area different from the first mentioned area, for supplying fuel to said grate as required to maintain a fuel bed of approximately constant resistance to gas flow therethrough.

2. The combination with a furnace comprising a grate on which solid fuel is burned, and having its primary air inlet and its outlet for gaseous products of combustion connected, one to the atmosphere by a passage of constant flow resistance, and the other to a draft creating device, of a differential pressure device comprising two pressure chambers each having a movable wall portion exposed externally to atmospheric pressure, a connection between the interior of one pressure chamber and the furnace interior immediately above the grate, and a connection between the other pressure chamber and the furnace interior adjacent the connection of the latter to the draft creating device, and fuel supply means automatically controlled by the resultant of the internal and external forces acting on said movable wall portions for supplying fuel to said grate as required to maintain an approximately constant ratio between the draft loss in the fuel bed and the draft loss in a portion of the furnace in which the flow resistance is constant.

3. The combination with a furnace comat prising a grate on which solid fuel is burned automatically res prising a grate on which solid fuel is burned and having its primary air inletand its outa let for gaseous products of combustion connected, one to the atmosphere by a passage of constant flow resistance, and having an adjustable secondar air inlet, and'the other atmosphere over one area, and the-resultant of the pressure in the furnace adjacent the draft creating device and the opposing-pressure of the atmosphere over an area difierent from the first mentioned area, for supplying fuel to said grate as repuired to maintain a. fuel bed of approximately constantresistance to gas flow thereth'rough.

' 4. The combination with a furnace comprising a grate on which solid fuel is burned and having its prima sultant of the Si New day of August A D. 1922.

air inlet and its outlet for gaseous pr acts of combustion connected, one to the atmosphere by a passage of contant flow resistance, and the other to a draft creatin device, of fuel supply means automatical y responsive to a orce proportional 'to the difi'erence between the resultant of the pressure in the furnace above the grate and the opposing ressure of the atmosphere over one area, an e reressure in the furnace adjacent the dragt creating device and the opposing pressure of the atmosphere over an area of adjustable size, for supplying fuel'to said grate as required to maintain a fuel bed of approximately constant resistance to gas flow therethrough.

ned at New York in the county of ork and State of New York this 19th GEORGE H. GIBSON. 

